PROJECT SUMMARY Indiana ranks 14th nationally in drug overdose deaths and, from 2016 to 2017, experienced the 3rd largest increase (22.5%) in overdose deaths. The CDC recently reported Indiana as one of only six states with a significant increase in emergency department visits for suspected opioid overdose. Yet, Hoosiers at risk for opioid misuse and other substance use disorders (SUDs) are unlikely to receive necessary services; Indiana - a largely rural state - ranks 46th in number of behavioral health treatment providers per individuals suffering addictions. By targeting rural counties in a Midwest state, our research team seeks to address the national opioid crisis at its epicenter. We will also focus on a population among those at greatest risk for opioid-related harms: youth involved in the juvenile justice system (YJJ). Among arrested youth, 78% have recently used illicit substances. Our research has shown that YJJ die at 1.5 times the rate of youth who have never been arrested, and a leading cause of YJJ death is drug overdose. The primary goal of our proposed project, Alliances to Disseminate Addiction Prevention and Treatment (ADAPT), is to address barriers to effective SUDs treatment of YJJ as identified by the substance use care cascade. We will accomplish our goal by creating alliances between the juvenile justice system (JJ) and community mental health centers (CMHCs) in 10 rural Indiana counties. These collaborative JJ-CMHC partnerships will facilitate SUD risk identification and service connection by JJ and enable timely initiation and engagement in evidence-based SUD treatment provided by CMHCs. ADAPT takes a two-pronged approach. First, we will employ a Learning Health System (LHS) model to develop alliances between JJ and CMHCs. Second, we will maximize opioid use prevention efforts by implementing a bundled treatment approach to improve screening, resource allocation, workforce development and evidence-based interventions (EBIs) that target a range of SUD risk levels. We hypothesize that ADAPT ? a combination of the LHS alliances and dissemination of targeted SUD EBIs ? will positively affect SUD and recidivism outcomes over time. We will conduct a hybrid type II comparative effectiveness, cluster randomized clinical trial to compare the LHS to the EBI interventions. In addition, we will employ sophisticated methodology, such as a sequential multiple assignment randomized trial (SMART) design, and leverage our expertise in linking administrative data from multiple health and justice systems, to assess these outcomes. We will utilize our expertise in implementation science, community-based research, clinical trials, cost- effectiveness research, and linking administrative databases, for research to assess the impact of these interventions on criminal recidivism and substance use outcomes, including transition to opiate use disorders and opiate overdose. We expect this project will guide future community-based efforts targeting the substance use care cascade among vulnerable populations.